Are you saying that youth (like moi) cannot express themselves adequately simply because they haven't say....gone thruogh a divroce of something really traumatic like that (that they have nothing to express!!!) which I find pretty ridiculous (I think we have more to express actually....) I am dreading the day when I sit at the piano as an adult and nothing comes out. Or are you refering to....well....I don't know....what are you refering to.....?
This is really a topic for another thread, but let me say this: IMO, someone who didn't have a certain experience is indeed less well qualified to express the associated feelings than someone who did have the experience. It doesn't really have to do with being young, but simply with having had the experience or not.
It is the same with writing an essay. How likely is it that a 16-year old can write a deep, insightful essay about unconditional love, losing a loved one, the debilitating pains of getting older and seeing one's facilities slowly vanish, and similar things.
Still, most people can somehow associate with a situtaion even if they haven't experienced it themselves. This may result in a decent interpretation of a piece, or it may not.
On the other hand, having had such experiences does not do any good, if they haven't been analyzed and understood, or if the technical facilities to express the associated feelings are missing.
When I listen to young people playing highly emotional pieces such as Liszt's Liebestraeume No. 3, Satie's Gymnopedies, or many of the later Beethoven Sonatas and chamber music in general, I am often surprised at how well it is executed, and I am often completely appalled at how flat it can sound. The same is true for adults playing those pieces.